The aim of reducing cycle times of semibatch-polymerization processes requires systematic investigations of the kinetics, careful adjustment of the desired polymer properties, proper thermal reactor design and reliable reactor safety assessment [1]. As a concrete example, a semibatch-copolymerization was carefully examined with respect to four different aspects. Thermo-kinetics of the reaction were investigated with isoperibolic reaction calorimetry and GC. In order to obtain reliable values for the overall heat transfer coefficient of the production scale reactor, cooling experiments were carried out with solvent and final copolymer solution as reactor content. For consistent reactor safety assessment additional investigations are necessary including case studies of breakdown incidences. These simulations were performed with a mathematical model based on the GC data and experimental vapor pressure curves. As a result of these calculations: a reduction of reaction time from 10 to 6 hours was possible. To convert into practice, it must be ensured that even in this shortened time a product of the same quality is produced.